1. Field of the Invention
The present invention relates to an electronic apparatus, such as an electronic camera, which incorporates a plurality of microprocessor units.
2. Description of the Related Art
An electronic camera becoming more widely used at present has a tendency to increase the number of pixels of an image pickup element employed in the electronic camera with the provision of more advanced functions. In the past, various kinds of control processes were performed by one microprocessor unit (hereinafter referred to also as “MPU (Micro Processing Unit)”). However, an electronic camera incorporating a plurality of MPUs has also been recently practiced to realize higher performance and higher functionality.
At the system startup of an electronic camera after power-on, the startup operation is performed by reading all of data, which is stored in a ROM (Read Only Memory) and requires initialization, into a RAM (Random Access Memory). At that time, a system has to be started up after the initialization of all of the data which requires the initialization. The data requiring the initialization includes, for example, not only setting values and correction values for a sensor and hardware which are necessary for picking up an image, but also setting values selected from a menu.
In the electronic camera having more advanced functions, the number of setting values which have to be set and selected is increased and the number of pixels of an image pickup element, such as a CCD (Charge-Coupled Device) or CMOS sensor, is also increased. Therefore, an amount of the data requiring the initialization tends to increase. For that reason, a difficulty arises in shortening a startup time of the camera. Hence, an image pickup operation cannot be started immediately even with pressing of a release button after the power-on, and a shutter chance is missed.
In a digital camera disclosed in Japanese Patent Laid-Open No. 2003-189165, to overcome the above-described disadvantages, a program is divided into two parts, i.e., one part required to start up an image pickup system and another part. After power-on, the program part necessary for the image pickup system is first initialized and started up. Then, the remaining part is initialized and started up. By first starting up only the program part necessary for the image pickup system, a startup time from the power-on to a photographing-enable state can be shortened to reduce a possibility that the shutter chance is missed.
Also, in a camera disclosed in Japanese Patent Laid-Open No. 2001-94844, management information necessary for reading and writing data from and in a memory card is saved/recovered respectively in response to power-off/on of the camera. This technique eliminates the need of newly reconstructing the management information for the memory card at the power-on. Accordingly, a time taken until the start of a photographing operation can be shortened to reduce a possibility that the shutter chance is missed.
In the digital camera disclosed in the above-cited Japanese Patent Laid-Open No. 2003-189165, however, the photographing operation is allowed at a point in time when the startup of the program part necessary for the image pickup system is completed. Therefore, the photographing operation is allowed in spite of a situation where there is actually an error in a memory card, or where the memory card has no vacant capacity and cannot store any more images even when the images are photographed.
The above-cited Japanese Patent Laid-Open No. 2001-94844 discloses the camera related to the technique of saving/recovering the management information necessary for the memory card, and it does not propose a method of avoiding prolongation of the system startup time, which is caused by an increase in the setting values required in the sensor and the hardware. Further, Japanese Patent Laid-Open No. 2001-94844 proposes a system incorporating a plurality of MPUs, but it has the following disadvantage. When the plurality of MPUs require the same management information, each of the MPUs has to save/recover the same management information, thus resulting in a longer startup time.